Tachometer.



Patented Apr I0, |900 Fv'g.

l/ /LM Mit/Emol? ATTOMLLN .lv AUMUND TAGHDMETER.

(Application Bled July 1, 1898.)

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WTNESSES.'

(No Modal.)

JOHANNES AUMUND, OF ZURICH, SlVITZERLAND. i

"moi-IOMErnie.V

srEcIFleArIorv fol-ming part of Letters Patent No. 646,940, dated April10, 1900. Application met my 1,1898. serai 110.684,961. no moat-.1.)

To all whom it may concern:

Be itknown that I, JOHANNES AUMUND, a citizen of the Republic ofSwitzerland, and a resident of Zurich, Switzerland, have inventedcertain new and useful Improvements in Tachometers, of which thefollowing is a full, clear, and exact speciiication.

In tachometers as heretofore known, fixed pivots were employed with pinsor fixed bearings for that part of the device which changes the pendulum-stroke into a reciprocating movement. It is to be understood that inthe former case the pins or pivots, weighted by the centrifugal force ofthe swinging pendulums, offer resistance to the free movement of thependulums by their friction, and that therefore the pendulums are notable to assume immediately after any variation of speed theircorresponding positions suited to the change. When the variation of thevelocity increases further, a certain yielding by impact takes place,causing the pendulums to swing beyond the real corresponding position.The consequence of this is a jerky movement or thrust of the indicator.To obviate this, artificial damping has been tried; but if the revolvingseesawing transmission piece is guided by fixed bearings anotherdrawback arises from the circumstance that risings are wrought on everyshaft or arbor from continual running in pillows or bearings, whichunevennesses will work corresponding hollowsinto the bearings, and thusform another obstacle to the free movement of the transmission-piece.Precise balancing ofthe indicator will become impossible from the saidcauses. Precision of indication depends more or less, but to a greatextent, on regular lubrication of this pillow and on the lubricatingmaterial employed. These drawbacks are overcome by the presentinvention, as all pivot or shaft bearings are avoided in the pendulummechanism and only a rolling movement is employed, which puts the leastresistance to the exact function of the swinging pendulums, and therebyrenders it possible that the indicator indicates in a manner free fromjerks and in true accordance with the go of the controlled machine.Finally, the attending to and lubricating of the interior elementsbecome superfluous, and wear and tear inevitable with pivots andbearings are excluded.

In the accompanying drawings, Figure lis partly a sectional View andpartlya side elevation of the device in its resting position orcondition. Figs. 2 and 3 represent transverse sections. Fig. 4represents the mechanisms in a casing, the pend ulums being in thevicinity of their extreme position, and hand, and a part of the dial. l

In the drawings, a, Fig. 1, is the drivingshaft, which carries a platea. On this plate or disk four racks b b are so arranged that their teethface each other. Four cog-wheels c c engage the racks,and between these,also engaging with toothed wheels, is a four-edged rack d, which istoothed at all four sides. One part of the cog-wheels c c carry theswinging pendulums e c,which encompass the racks with forked arms, Fig.l, and these governorpcndulums tend to revolve the wheels by thecentrifugal force produced by the rotation of the shaft ct and todisplace thereby the rack d. The racks b b are connected at theirextremities by a cruciform plate f, which carries a collar g. Thiscollar or sleeve has an interior thread at g,and the piece h is screwedtherein. The one extremity of the tension-spring 7c props against thepiece h, and its other end rests against a space of the rack d, and thusmaintains equipoise against the displacement caused by the centrifugalforce by its pressure. The collar g is provided at g" with annularinterior grooves, so that it represents a rack in longitudinal section.l Into this collar the cog-wheels it are set, which engage the saidripples of the collar and which guide between them the rippledcylindrical extension of d, which also representsa rack in itslongitudinal section here. Each group of. cogwheels have a uniformnumber of teeth, and each wheel is provided with conical extensions aptto secure exact guidance of each other. These extensions are in contactwith those of the neighboring wheels, the conical wheels thus workingtogether. Fig. 2 shows this arrangement for the wheel group c c and Fig.3 for the wheel group t' t'.

While the pendulum traverses the way from c to e2, Fig. 4:, the wheel crolls from c" on the rack h and therein displaces the rack which lIco isengaged therewith. As all wheels of this group have a uniform number ofteeth and are engaged with the rack d, all Wheels advance or return onthe same length of way with the pendulum movement. Therefore they alwaysremain in the same position to each other and are always guided alongeach other by their cones. The same is true of the wheels of group z't', which also move with the movement ot the rack d equal to half of theWay from d, and they are always kept in the same position to each otherand guide each other by their cones. The movement of the part d causedby the pendulum-stroke is then appropriately transmitted to the hand bythe lever Z and wheels m and n.

As shown in Fig. 4, the effective pendulumarm shortens at the stroke ofthe pendulum. This arm finds its pivot in the pitch-line of the rack band is equal to ce c' when at rest, and near the extreme position it isequal to x e. Thereby with lesser velocities a comparatively-greaterenergy is obtained in comparison with greater velocities, and theetticacy of the spring is less influenced at equal. z5

variations of velocity when their limit of elasticity is approached.Thus the spring is relieved and the purpose of maintaining the scale inthe Widest possible limits is served.

I claim- In combination in a tachometer, the governor parts arranged tomove by centrifugal force, the cog-wheels connected to said parts to berotated by the movement thereof, the transmitting-rack d meshing withthe cog# wheels, said cog-Wheels serving as bearings for the rack Vandhaving conical faces by which they guide each other, and the guideracksmeshing with the cogwheels and rotat-` ing with the driving-shaft,substantially as described.

In testimony whereof I have hereunto set my hand in presence of twowitnesses.

JOHANNES AUMUN D.

Witnesses:

KARL KARAscKN, FRIEDRICH ALBERT GRIGER.

